Contrast-induced nephropathy (CIN) is a form of acute kidney injury attributed to the use of iodinated contrast media for diagnostic and therapeutic procedures. The risk of CIN is high in patients with renal insufficiency or cardiovascular pathologies and in those undergoing invasive coronary angiography. Prophylactic hydration with intravenous saline, prior to the administration of contrast medium, is recommended to help prevent CIN in high-risk patients (although recent evidence disputes this recommendation). Researchers in Italy tested whether the hydration status, measured by bioimpedance vector analysis (BIVA), could predict which patients would experience CIN, and they published their findings in the Journal of the American College of Cardiology.

The single-center study enrolled 900 patients with stable coronary artery disease (CAD) who were scheduled for coronary angiography using iodixanol contrast medium. Patients received saline hydration for 12 h before and after the procedure. Serum creatinine was measured before the procedure and on consecutive days afterwards to diagnose CIN. Bioimpedance measurements were taken immediately before the administration of contrast medium, using a tetrapolar impedance plethysmograph (EFG electrofluidgraph, Akern). Values of resistance (R), reactance (Xc), and impedance (Z) were normalized to height (H).

Overall, CIN occurred in 54 patients (6.0%). Patients who experienced CIN had significantly higher R/H and Z/H ratios, indicating lower hydration status. No difference between groups was seen in the Xc/H ratio or phase angle. Statistical analysis showed that lower fluid status (higher R/H ratio) was a significant and independent predictor of CIN in patients with stable CAD. The authors conclude that “point-of-care BIVA is a user-friendly, rapid, simple tool for assessing peri-procedural fluid levels in patients with CAD undergoing contrast medium administration. It allows identification of patients at high risk for developing [CIN].”